Narrow-Frame Laser Backlight Layout for Uniform LCD Color
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Solution Overview
Problem
Existing edge-lit type liquid crystal displays face challenges with visible end emission semiconductor lasers due to large size, low efficiency, high cost, complex structure, and non-uniform brightness distribution, which are exacerbated by high power consumption, thermal issues, and anisotropic beam divergence, leading to non-uniform color distribution and increased costs.
Innovation Solution
A laser backlight structure for edge-lit type liquid crystal displays that uses end emission visible lasers with beam shaping devices and reflectors to expand and overlap laser beams over a larger area on the light guide plate, reducing the frame width and enhancing uniformity, while minimizing the number of lasers required and addressing cooling issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If end emission visible lasers are used as light source, then color quality and monochromaticity are improved, but device size and structural complexity increase
Solution Approach 1:
The patent divides the laser light source into multiple independent laser chips (red, green, blue) that are separately mounted on the light guide plate. Each laser chip is packaged individually with simplified structures, avoiding the need for a single complex integrated laser package. This segmentation allows each laser to be optimized independently while maintaining overall system simplicity.
Solution Approach 2:
The patent transitions from conventional end-emission laser geometry to side-emission laser geometry, where the laser beam propagates parallel to the light guide plate surface rather than perpendicular to it. This dimensional change in beam propagation direction enables more efficient light coupling and uniform distribution across the display area.
2Illumination intensity
If laser beams are emitted with high power density, then light intensity is improved, but damage to light guide plate and thermal issues occur
Solution Approach 1:
The patent applies different optical properties to different regions of the light guide plate. Scattering regions with specific optical characteristics are created at precise locations where laser beams enter the plate. These localized scattering regions distribute the laser energy uniformly, preventing concentration of high power density at any single point and thereby avoiding damage to the light guide plate.
Solution Approach 2:
The patent introduces scattering regions as intermediary elements between the laser beams and the light guide plate bulk. These scattering regions act as mediators that convert the highly directional, high-intensity laser beams into uniformly distributed light, preventing direct high-power density interaction between the laser and the light guide plate material.
3Stability of the object's composition
If beam divergence angle is reduced for uniformity, then color uniformity is improved, but light coverage area decreases
Solution Approach 1:
The patent employs adjustable beam expanding lenses that can dynamically control the beam divergence angle. By adjusting the lens parameters, the system optimizes the balance between beam convergence (for uniformity) and coverage area, allowing adaptive optimization based on different operating conditions and display sizes.
Solution Approach 2:
The patent changes key optical parameters including beam diameter, divergence angle, and wavelength by selecting appropriate laser chips and optical elements. By adjusting these parameters, the system achieves both sufficient beam spread for wide coverage and controlled divergence for uniform color distribution across the display area.
4Illumination intensity
If multiple laser chips are used for white light synthesis, then color rendering is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent segments the white light generation process into multiple independent laser chips (red, green, blue) that are separately manufactured and mounted. Each laser chip can be produced using standard semiconductor fabrication processes, and the segmentation allows for independent optimization and replacement of individual color components, simplifying manufacturing and quality control.
Solution Approach 2:
The patent merges multiple discrete laser chips emitting different colors onto a single light guide plate, combining their outputs to create white light. This merging approach allows for efficient space utilization and simplified optical path design compared to sequential generation methods, while maintaining the advantages of laser monochromaticity for each color component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves a uniform light field distribution, reduces laser usage and costs, and extends the service life by optimizing beam overlap and reducing thermal stress, resulting in a narrow-frame appearance with improved color uniformity and reduced speckles.
Implementation Method 1
a beam shaping device is present between the lateral light-permeable surface of the liquid crystal display light guide plate and the reflector, wherein the beam shaping device is configured to expand laser beams
Implementation Method 2
at least one reflector is present on a position close to the lateral light-permeable surface of the liquid crystal display light guide plate... laser beams emitted by visible end emission semiconductor lasers are reflected by the reflector
Implementation Method 3
Several scattering regions present on a surface (length × width) of the light guide plate are used to damage total reflection of light in the light guide plate, so that a surface light source is formed on an emergent surface of the light guide plate
Data Source
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AI summary
The invention discloses a laser backlight for a narrow-frame edge-lit type liquid crystal display. The laser backlight includes visible laser groups, beam shaping devices, reflectors and a liquid crystal display light guide plate. After being reflected by the reflectors to change a laser propagation direction by 180 degrees, laser beams emitted by visible lasers are incident on the liquid crystal display light guide plate through a light-permeable surface. When being incident on the lateral light-permeable surface of the liquid crystal display light guide plate via the reflectors, the visible laser beams emitted by the adjacent visible laser groups generate a light overlap larger than 10% of an area of each light spot. A sum of lengths of laser spots of the visible laser groups at a same waveband on the lateral light-permeable surface of the liquid crystal display light guide plate is greater than or equal to 0.65 time of a length of the light-permeable surface. The invention can achieve an effect that a liquid crystal display gains the best brightness of a screen and the best brightness and color uniformity of pictures by using a minimum number of visible lasers.